Hoisting block



Jufie 8,1926; 1,588,115

J. W. KITTREDGE HOISTING BLOCK Filed May'14. 192] 2.Sh eets-Sheet-1Fig.1.

June" 8 1926.

' Filed May 14, 1921 1,588,115 J. w. KITTREDGE HOISTING BLOCK2'Sheets-Sheet 2 E Xqdenforrfl atented .lune 8, 1926.

.UNTITEDQSJTVATEJS ATENT oFFicE. j

JOHN w. xrrrnnnen, or AKRON, 01110.

norsrnve BLOCK.

- Application filcd May 14, 1921. Serial No. 469,457.

I My invention relates particularly to an attachment to hand power chainblocks to prevent their being blocks are used for lifting heavy weightsand their first and foremost requirement is absolute safety. It is wellknown, however, that through carelessness and ignorance very manyblocksare at some time loaded beyond their proper working strength,thereby breaking them or injuring them so as to make them unsafethereafter. The objects of my invention are 1st. To provide a block withholding mechanism to hold it against backward movement, and with theparts between the holding mechanism and the 1ifting wheel, of gearing orother positive mechanism, so that there can be no possibility of theload slipping. I c

2nd. To provide a release between-the driving wheel and the holdingmechanism which shall automatically release at a certain forward torqueon the driving wheel, thereby rendering it impossible to lift a loadbeyond the working strength of the block.

3rd. To have the release such that while it will not raise an excessiveload, it will lower it to the floor, should such excessive load comeupon the block through accident or any means other than the blocks ownlifting mechanism.

4th. To have the said release such that it will automatically grip andliftits proper load as soon asthe excessive load is re lieved. 1

5th. To have all parts simple and protected from accidental injury. 7

I have shown in the drawings a spur geared block with the brake of myco-pending patent application No. 356,235; but my invention can beapplied to worm blocks, to hoists with direct drive, to those with screwand ratchet brakes, to power driven hoists and to a great variety ofother types. The holding mechanism may be the lifting .nechanism, as inthe case of the worm block, or it may be an independent brake asherewithshown;

I attain theforegoing objects by the mech anism shown in theaccompanying drawings, in which ic Fig. 1 is a longitudinal section online overloaded. Chain EE of F ig. '2; and Fig. 2 is atransverse"section on line -A-B' CDv of Fig. 1, with the plate and the nut46removed.

Parts fastened rigidly together are crosshatched alike, even though theymay be separate pieces of metal. For clearness of description, a givenpart is designated by a numeral, as 47, and different edges or faces ofthat part by that numeral with letters, as 47 47 etc. A given piececarries the same number'throughout the several views.

The blocklis hung from an overhead support by the hook 1, which isattached tothe gear case 2 and the brake case 3 by the} swivel bar 4.Bolts 25 and spacers 26 bind the cases firmly together. A liftingsprocket 5. is journaled in hearings in the cases 2 7 and 3, and itcarries a liftingjchain 6 and a lifting hook 39. The arrows, in everycase, indicate theparts running in the direction to lift .theload. Thedrive shaft 9'passes centrally through the lifting sprocket 5 and P isjournaled in beari'ngs therein. 1 Thewheel 8 with its lug 8 turns freelyon the drive shaft 9 through a partial revolution. Lug 8 actuates thelever 31- and lever 31 in turn actuates the drive shaft'9 to which itrigidly keyed. The drive shaft 9 actuates the lifting sprocket 5' andthe lifting'chain 6 through the planetary gearing shown. in

Fig.1 and common in chain block construction. v

The leverSl isconnected to theinternal brake band 29 by the lever 34 andthe shoes 32 and 33. The wheel 8' and lug 8 col lapse the band and causeit to turn freely; but the load on hook 39, acting through the driveshaft 9, expands the hand against its enclosing walls and causes it tobind and hold the load. i

Integral with the wheel 8 is the threaded portion 83. The wheel 47 has acorrespondlng threaded portion 47 engagingB Integral also with the wheel47 is the lug47 A stud 48 is set in the wheel 8 and extends through aslot inwheel 47. A spring 49 extends from the lug 47 to the stud 48 andtends to screw the wheels 8 and 47 closely together. The sprocket 50fits against a slip;

50 carries the hand chain 7. The plate 15 issimply a protecting cover.

The operation of the block is as follows The, operator pulls the chainin the direction of the arrow, and thereby actuates the sprocket 50.Sprocket 5O binds with wheel 47 through heavy,friction andtturns itarrow-wise. WVheel 47 through lug 47 spring 49 and stud 48 turns wheel8;;arrowwise and, within the strength of the spring 49, these parts allmove together as-asingle rigid piece; And wheel 8, through its lug 8t;lever "31, drive shaft 9, sprocket 5 andthe connecting gears, actuatesthe=chain Gand the hook 39- andliftstheload. When, however, the load isexcessive, the wheel'S-jand the studSremain stationary. As the operatortheni pulls the chain 7* arrow-wise, the sprocket 50 turns on the ballbearing 51 and turns wheel 4E7 "with it through friction the spring; 49yields; and the" wheel 17' screws away from the wheel 8- untilthefriction between wheel Hand sp rocket- 5O issufficien-tly relievedto, allow sprocket 50 to By, making thespring, 49' of proper strength,it .will transmit torque suiiicientto lift' a' proper load, but"willyield' within the'working strength of the blockandpreventoverloading. When. the. excessive load is relieved,,the;s1'iinga9 at once expands, screwing the. wheeltti tightly down onthe wheel 8,.causing heavy friction between Wheel iffandsprocket .50, and, againtrans: mittingsuificienttorquegto lifta proper load:

Suppose now that an excessive load should be put upon the block throughindependent means; as that, it should/be hooked to the block andlthenthe supports taken from beneathit: It would act upon the sprocket 5, thegearing, the drive shaft and the brake, and these would hold itpositively to the limit of their strength. The slip member, beingbeyondthe brake, wouldnot affectihe holding in any way whatsoever. Itwould,

however, prevent lifting the load higher as justdescribed. Suppose now,the operator, finding the load excessive, wishes to lower it to thefloor. He pulls the chain 7 counterarrow-wisc. The chain pull, aswell,as'the force of the spring, tends to screw the wheels 47 and 8.together, firmly, gripping the sprocket 50, and he thus lowers the loadto;;th e floor.

The maximum forward torque on the driving wheel 50iscontrolledby thespring 49-," the-strength of which is approximately constant, and not bythe coefficient offriction'which is widely variable. Suppose-twoblocks-withisprin-gs 49 equal 'to each other; thejfirst with oil '-onthefriction' surfaces of wheel 47, and" sprocket! 50'; the second withsaid' surfaces dry andrusted: Qn-the. first, slipping Wlll occur whenthe pressure beto physical position. driving member 50 actuatcs theclutch-meme coefficient of friction, the smaller will be the pressure,and their product, which controls theslip, willbeapproximately constant.

Similar construction can be applied to hoistsand blocks of other typesas hereinbefore described.

In the following claims, the word between is intended to have referenceto the sequence; of j'the driving operations, and not F or instance,if'the bers47' andS, and the member Sthen moves the friction'meniber 29,the members i? and 8 are said to be between the; driving; member' 50'and the friction member 29, even though they should not-be'b'etween themin physical position.

Having thus described my invent-ion, 1 claim as new and desire to secureby Let ters Patent 1. Incombination, a hoistingblock comprising adriving member, a driven member, said driven membenadapted t'ocarrya-pload, avdrive connection from said driving member to said drivenmember, friction membersbe tween said driving and driven members adaptedto hold the load through friction against baclnvard' movement,andfriction clutch members between the drivingmember and thesaidfriction members, the an rangement being such that backward torquedrive conuecticn from the; cont-milled].eic

ment' to the driven wheel including positive driving);elements,thearrangement being such baclw .sd tcrque upon the driving clutch member:causes the clutchmembers to grip, that a given forward torque upon thedriving clutch member causes the clutch members to release, ant that theclutch members grip automatically whenever the torque on thedriving-clutch member-is less than the-given torque aforesaid.

3. In combination, a heisting block com prising a driving member, adriven memher, a drive connection therebetween, a brake adapted toretard an element of, the said drive connection against backwardrotationfsaid drive Connection from the retarded element to the drivenmember being positive drivingmembers, and a slip clutch in the saiddrive connection.

4. In combination, a hoisting block comprising a driving member, adriven HIGH}? her, a drive connection from the driving member to thedriven member, a brake,fsaid brake retarding an elementof'the said driveconnection against backward rotation, the said drive connection from thesaid retarded element to the driven member being positive drivingmembers, a friction clutch in the said drive connection between thedriving member and the said retarded element, a spring in the saidfriction clutch, and connectingmeans whereby it exerts pressure betweenthe friction surfaces'of the clutch and whereby the forward torque ofthe driving member tends to relieve the said pressure. 1 v

5. In combination, a hoisting block comprising a driving wheel, a driveshaft, a driven wheel, a positive drive connection from the drive shaftto the driven wheel,-a friction brake, a connection from the brake tothe drive shaft, a drive connection from the driving wheel to the driveshaft through the said brake connection, a friction clutch in the saidlast mentioned drive connect-ion, and a spring in the said frictionclutch adapted to exert pressure between the friction surfaces thereof.

6. In "combination, a hoisting block comprising a driving member, adriven memher, a clutch member, the clutch member be ing in frictionalengagement with the driving member, a positive drive connection from theclutch member to the driven memher, a screw on the clutch member wherebysaid clutch member tightens or loosens its frictional engagement withthe said driving member, a spring'acting on the said-clutch member, thedirection of the screw being such that the spring tends to tighten thevsaid frictional engagement and the forward torque} of the driving{member ,tends' to loosen it. V

7. In a hoisting block, the combination of a screwthreaded clutchmember, a second clutch .member, said clutch members havlng conesurfaces in engagement, a' spring adapted to turn'the'screw member andthere- 8..In con'ibination, a hoisting block comprising adrivingwheel,adriven wheel, a gear drive adapted to drivethe said driven wheel,driving means fromthe driving wheel to an element of the said geardrive, a'fric tion clutch 'in thesaid driving means, a spring in thesaidfriction clutch adapted'to exert pressure between the friction surfacesthereof and to yield at a given-forward torque ofthe driving Wheel and.thereby relieve the said'pressure, a brake, connect-' ingfmeans from thebrake to an element of thesaid gear drive wherebybackward torque of thesaid element tends to set the brake and forward torque-of the saidelement tends to release the brake, and means where; by backward torqueof the driving wheel tends to release the said brake.

9. In combination, a hoisting block comprising a drive shaft, a drivenmember,a

driven member, a friction brake, a positive connection from the braketothe drive shaft, friction clutch elements, spring means adapted topress the said clutchelements into driving frictional'engagement and toyield at a given forward torque of the driving clutch element andthereby release the clutch elements, and a driveconnection from thedriven clutch element to .the drive shaft through the brake connection.10. In combination, a hoistingblock comprising a frictionclutclrniechanisin, spring means in the said clutch-mechanism adapted topress the friction; surfacesthereof into driving frictional engagement,"a lifting mechanism, said lifting mechanism comprising a lifting wheel,a planetary gear train, a drive shaft thereto,"and abrake, and a driveconnection from the driven, clutch element through said brake to theshaft.

gear c'onn'ectioirfrom the drive shaft to the lill) 1].. In combination,a hoisting block comdrive shaft, a friction clutch in the said drivingmeans, a spring connected to the driven clutch member, means whereby itex erts pressure between the members of said clutch and whereby theforward torque of'the driving wheel reduces thesaid pressure, a brake,and a direct connection from the brake to the drive shaft.

. 12. In a hoisting block, the combination of a driving sprocket, adriven sprocket, a lifting chain fitted to the driven sprocket, a clutchwheel bearing on one side of the driving sprocket through a frictioncont-act, a second wheel bearing on the opposite side of the drivingsprocket with less friction therebetween than in the friction contact ofthe clutch'wheel, ascrew connection between the two said wheels, aspring'connection bcward rotation of the clutch releases the said brake.

21. In a hoisting block, the combination ing sprocket through a frictioncontact, a

second wheel bearing on the opposite side of the driving sprocket withless friction therebetween than in the, friction contact of theclutchwheel, a screw connection between the two said wheels, a springconnection between the said wheels tending to screw them together, thedirection of the screw such'that the forward torque of the drivingsprocket tends to screw the two said wheels ed to control an element ofthe said drive connection in its backward rotation, and the element tothe driven sprocket being positive driving element.

I 22. In a hoisting block, the combinatio of a friction clutchmechanism, screw elements therein, a spring connection between the saidscrew elements whereby the said elements press the clutch surfaces intodriving frictional engagement, a. driven wheel, a drive connection fromthe-driven clutch element'to the drivenwheel, a brake adapted to controlan element of said drive connection in its backward rotation, and thesaid drive connection from the retarded ele ment to the driven wheelcomprising posi- May, 1921. v p

- p JOHN W. KITTREDGE.

said drive connection from the controlled

